Activation Analysis of Large Samples
Published Online: 29 SEP 2008
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Bode, P. 2008. Activation Analysis of Large Samples. Encyclopedia of Analytical Chemistry. .
- Published Online: 29 SEP 2008
There is a trend in many analytical techniques towards the use of smaller sizes of the test portion, and sometimes submilligram amounts are being used. The limitation to the size of the test portion can pose the analyst with problems when the amount of material collected is large. Subsampling and preparation of a representative test portion may be difficult if homogenization is impossible or extremely expensive, or if homogenization introduces contamination. An alternative approach has been introduced in the 1990s by the development of large sample neutron activation analysis (LSNAA), later followed by large sample photon activation analysis. These techniques are capable of direct analysis of samples with masses of hundreds of grams to several kilograms. Though the principles and physics of large sample activation analysis are thoroughly understood, the method is still not as versatile or applicable as, for example, normal small sample neutron activation analysis. In this article, the physics of LSNAA is described, including methods of calibration. Examples are given of irradiation and counting facilities and the special aspects of quality control are discussed. Several examples are given of applications of large sample analysis, e.g., for studies related to electronic waste, complete archaeological and cultural artifacts, high-purity materials, and materials of irregular shape.